CA1178861A - Drill hammer with variable air consumption - Google Patents
Drill hammer with variable air consumptionInfo
- Publication number
- CA1178861A CA1178861A CA000394041A CA394041A CA1178861A CA 1178861 A CA1178861 A CA 1178861A CA 000394041 A CA000394041 A CA 000394041A CA 394041 A CA394041 A CA 394041A CA 1178861 A CA1178861 A CA 1178861A
- Authority
- CA
- Canada
- Prior art keywords
- chamber
- hammer
- spacer
- piston
- drill
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Earth Drilling (AREA)
Abstract
DRILL HAMMER WITH VARIABLE AIR CONSUMPTION
Abstract of the Disclosure A drill hammer which utilizes pressurized air for reciprocating a piston to provide a percussive drilling force to the drill bit is shown. The hammer includes a cylindrical housing having a top sub-member threadedly received therein for mating with the drill string. The housing also defines a chamber enclosing the reciprocal piston between an upper member and the axially lower drill bit. A spacer member is releasably attached to the upper member and within the chamber to displace a predetermined volume of said chamber.
Spacer members of various volumes are provided to thereby vary the volume of the chamber in accordance with desired air consumption for the hammer. Removal of the top sub permits withdrawal from the chamber of the top member and spacer member which are maintained together by a removable pin, permitting the spacers to be readily changed in the field for altering the consumption characteristics as dictated by drilling conditions or other variables in the field.
Abstract of the Disclosure A drill hammer which utilizes pressurized air for reciprocating a piston to provide a percussive drilling force to the drill bit is shown. The hammer includes a cylindrical housing having a top sub-member threadedly received therein for mating with the drill string. The housing also defines a chamber enclosing the reciprocal piston between an upper member and the axially lower drill bit. A spacer member is releasably attached to the upper member and within the chamber to displace a predetermined volume of said chamber.
Spacer members of various volumes are provided to thereby vary the volume of the chamber in accordance with desired air consumption for the hammer. Removal of the top sub permits withdrawal from the chamber of the top member and spacer member which are maintained together by a removable pin, permitting the spacers to be readily changed in the field for altering the consumption characteristics as dictated by drilling conditions or other variables in the field.
Description
7~8~ii The present invention relates generally to a fluid-driven hammer and more particularly to a down-the-hole air-operated rock drill hammer.
Air~operated rock drill hammers generally include a cylindrical body portion having a central chamber housing an axially reciporcal piston which provides hammer blows to a drill bit connected to the cylindrical body-and extending axialiy into the chamber. Air passages are provided for delivering pressurized air to reciprocate the piston for alter~nately striking the hammer and recovering to a raised position sub-adjacent the top of the chamber. An air hammer of the above general characteristics is more completely described in co-pending U.S. Patent No. 4,312,412, issued January 26, 1982 of common assignee of the present invention.
Generally, drill hammers of the above type utilize a constant volume o~ air at a predetermined operating air pressure as delivered from a compressor. In determining the operating pressure for the hammer there are basically two rules: (1) The greater the air pressure delivered to the hammer, the faster the piston reciprocates while delivering blows of grea$er force. This normally results in a faster rate of penetration however, at some point an excess air pressure or energy will be of no further assistance in breaking the rock. But even then, excess air may be required to obtain sufficient volume adequate to clean the hole and
Air~operated rock drill hammers generally include a cylindrical body portion having a central chamber housing an axially reciporcal piston which provides hammer blows to a drill bit connected to the cylindrical body-and extending axialiy into the chamber. Air passages are provided for delivering pressurized air to reciprocate the piston for alter~nately striking the hammer and recovering to a raised position sub-adjacent the top of the chamber. An air hammer of the above general characteristics is more completely described in co-pending U.S. Patent No. 4,312,412, issued January 26, 1982 of common assignee of the present invention.
Generally, drill hammers of the above type utilize a constant volume o~ air at a predetermined operating air pressure as delivered from a compressor. In determining the operating pressure for the hammer there are basically two rules: (1) The greater the air pressure delivered to the hammer, the faster the piston reciprocates while delivering blows of grea$er force. This normally results in a faster rate of penetration however, at some point an excess air pressure or energy will be of no further assistance in breaking the rock. But even then, excess air may be required to obtain sufficient volume adequate to clean the hole and
(2) The greater the volume of air passing through the hammer chamber, the greater the penetration rate due to increased hole cleaning or bailing capabilities of the increased air volume.
Thus, based on these two rules, ideally a compressor would be chosen having a volume and pressure capabilities to optimize the air volume at a set pressure to power the hammer and clean the hole.
However, the hammer acts in reverse to the compressor in that the high pressure air causes the reciprocal movement of the piston. In so doing, the hammer has built-in characteristics (i.e. piston weight and travel, chamber size, - 1 - '~$
sb~
.
li7~861 etc.) that only permit it to accept a given volume of air at a predetermined pressure. Thus, if the volume of air capable oE passing through the hammer chamber is insufficient to bail the hole upon exiting the hammer, supplemental air must be routed through the hammer (i.e. without passing through the chamber) in a manner to provide sufficient air volume downhole to keep the hole clean. This additional air, although compressed by the compressor, is seen to have done no drilling work by powering the hammer, thereby decreasing the efficiency Of the total operation.
The preferred situation would be to match a hammer to the compressor so that the hammer is capable of passing all the compressed air through the piston chamber at a volume sufficient to also bail the hole. However, because of the nature of the hammer, the operating characteristics of the hammer remain generally constant and the only variable in prior art hammers is to provide a choke member in the air by-pass tube to establish the necessary volume of by-pass air to mix with the air discharged from the piston chamber to bail the hole.
According to the present invention there is provided a rock drill hammer operated by a pressurized fluid for providing hammer blows to a drill bit, the hammer having a cylindrical hammer body defining an internal chamber with a movable piston mounted in the chamber for axial reciprocal movement between an upper position adjacent the upper end of the chamber and a lower position, a drill bit axially extending into the chamber from the lower end and providing a surface for receiving the blows of the piston on its downward movement. An upper member defines the upper end of the chamber and a lower member defines the lower wall of the chamber, and a spacer means is removably attached within the chamber adjacent at least one of the members to fill a pre-determined portion of the chamber to alter the air consumption of the hammer at any given pressure.
It can be seen, therefore, that the present invention provides a fluid or air-operated hammer of the above sb/J~
1~7886~
type having interchangeable spacer members to, upon replacement r change the volume of the piston chamber of the hammer to enable the hammer to, upon such modification, utilize different volumes of air at a single pressure (i.e. depending upon the volume necessary sb/~ - 2a -.
7~61 to bail the hole). As the components of the hammer that determine the air flow amount is the volume of the piston chamber with the piston residing therein, spacers of various volumes placed in the chamber thereby alter the available chamber volume so that all the air delivered can be efficiently utilized to power the hammer prior to being discharged to bail the hole.
Description of the Drawings .
Figure 1 is a cross-sectional elevational view of a rock drill hammer with a reciprocating piston and having a spacer of one dimension according to the present invention;
Figure 2 is an enlarged sectional view of a portion of the hammer of Figure 1 and showing a spacer of a larger configuration to alter the hammer characteristics in accordance with the present invention;
Figure 3 is an exploded isometric view of the top member and spacer member of Figures 1 and 2; and Figure 4 is a view similar to Figure 2 of an alternative embodiment of the invention.
Description of the Preferred Embodiment -Referring to Figure 1, a fluid-operated rock drill hammer 10 is shown in position for drilling as resting on the bottom 12 of a borehole 11. The hammer 10 comprises a cylinder 13 with a drill chuck 14 supported at the lower end.
The drill chuck 14 receives a drill bit 15 retained in the chuck 14 by retaining ring 16 and axially projecting into the cylinder 13. The cylinder 13 is closed at its top end by a top sub 35 threadedly connected thereto which in turn is threaded to the drill string (not shown) for delivery of compressed air to the hammer.
A feed tube 17 is mounted coaxially in the cylinder 13 and extends from the upper end of the cylinder 13 toward the chuck 14 terminating just above the drill bit 15. At the upper end, the feed tube extends through an upper member 30 defining the top of the chamber to be in fluid flow communication with the ports of a check valve 32 housed in the top sub 35. The upper member 30 is retained in position by an upper annular guide member 34 and an annular washer 36 so that tightening the top sub 15 into the chamber 13 '7~61 completes the assembly.
The opposite end of the feed tube 17 is restricted or blocked by a choke 18 that blocks the fluid flow through the feed tube 17 providing higher presser in that portior, of the tube above the choke 18. A single set of pressurizing apertures 19 is provided in the wall of the feed tube 17.
The apertures 19 include four individual apertures spaced circumferentially around the tube 17 at a single axial position upstream of the plug 18. Exhaust ports 27 are provided in the tube below the choke 18.
An annular piston 22 is slidably mounted in the cylinder 13 to axially reciprocate within the chamber defined by the retaining ring 16 forming the lower wall member of the chamber and the upper member 36 defining the upper wall member. The piston 22 includes a channel 21 extending around the internal piston wall for fluid flow communication through longitudinal passageway 25 in the piston to the lower surface 20 of the piston 22. A second diametric channel 23 extends around the internal piston wall below the previous groove and is connected through longitudinal passageway 26 to the end face surface 24 at the upper end of piston 22. Thus, it is to be understood that through these various ports and passages pressurized air is delivered either to the upper surface of the piston 22 causing it to deliver a downward hammer-like blow to the bit 15, or to the lower surface 20 elevating the piston 22 to its upper position in preparation for the downward blow.
In accordance with the present inven~ion, the volume of the chamber defined between the upper member 30 and the retaining ring 16 is selectively modified by attach-ing to the upper member 30 a disc-like spacer 38. Thus, referring to Figures 1-3 (particularly Figure 3), it is seen that the upper member 30 defines an axially downwardly extending annular neck portion 31 surrounding the feed tube 17. The spacer 38 defines a concentric cGuntersunk opening for mating with the neck portion 31 with the upper annular surface 39 abutting the lower surface of the top member 30 and a lower surface 40 defining the top boundary of the piston chamber. The facing axially extending surfacas of the neck portion 31 of the spacer defines an annular groove 42 in axial alignment with openings 44 extending through the spacer member 38. A pair of removable mounting pins 48 are inserted in the openings 44 to seat within the groove 42 for retaining the spacer 38 on the member 30. The mounting pins 48 are held in position by the internal wall of the chamber during operation of the hammer.
Reference is now made particularly to Figure 2 which is an enlarged view of the upper portion of the hammer 10 showing the spacer 38 having greater axial dimension than the spacer member of Figure 1 so as to extend further into the chamber to displace air volume and thereby alter the air consumption characteristics of the hammer in accordance with a predetermined optimum air consumption.
Referring now to Figure 4, an alternative embodi-ment of the invention is shown. As therein seen, the spacer member 38a is a cylinder having an axially extending wall adjacent the inner wall of the chamber and thereby defining a reduced diameter upper portion of the chamber (as opposed to a reduced axial dimension to the upper chamber as in the previous Figures). To accommodate this configuration, it is noted that the piston 22 has a reduced diameter upper portion 22a that fi~s within the reduced diameter of the spacer 38a so that the piston is not restricted from its full axial reciprocal movement.
As before, the spacer 38a is removably retained in position by a shoulder 5a on the outer wall of the spacer engaging a mating annular shoulder within the chamber. Thus tightening the sub 15 against the washer 36 plaaes a retain-ing force on the spacer 38a during operation of the hammer, but permitting easy field replacement of a spacer of a lesser wall thickness to increase the chamber volume.
It should al~o be noted that this second configura-tion is easily adapted to attachment to the retaining ring16 at the lower end of the chamber (with the lower end of the piston requiring a reduced diameter portion similar to the upper portion herein above described) to similarly effectively change the volume of the chamber of the hammer , ...
:~17~86~
as desired in the field, with either one or both upper and lower spacers being used as desired.
Thus, it is seen that to change the hammer 10 .rom one set of operating characteristics utilizing a certain volume of air at a given pressure to utilizing a different volume of air at the same pressure, the top sub 15 is threadedly removed from the top of the cylinder 13 exposing the top guide 34 and the top member 3 a to be readily removed.
By removing the top member 30, the appropriate size spacer 38 can be inserted to alter the chamber volume in a manner that permits, for the most part, all the compressed air to be passed through the chamber prior to being exhausted through the bit for bailing the hole, thereby utilizing more of the compressed air for drilling the hole making the total operation more efficient.
Thus, based on these two rules, ideally a compressor would be chosen having a volume and pressure capabilities to optimize the air volume at a set pressure to power the hammer and clean the hole.
However, the hammer acts in reverse to the compressor in that the high pressure air causes the reciprocal movement of the piston. In so doing, the hammer has built-in characteristics (i.e. piston weight and travel, chamber size, - 1 - '~$
sb~
.
li7~861 etc.) that only permit it to accept a given volume of air at a predetermined pressure. Thus, if the volume of air capable oE passing through the hammer chamber is insufficient to bail the hole upon exiting the hammer, supplemental air must be routed through the hammer (i.e. without passing through the chamber) in a manner to provide sufficient air volume downhole to keep the hole clean. This additional air, although compressed by the compressor, is seen to have done no drilling work by powering the hammer, thereby decreasing the efficiency Of the total operation.
The preferred situation would be to match a hammer to the compressor so that the hammer is capable of passing all the compressed air through the piston chamber at a volume sufficient to also bail the hole. However, because of the nature of the hammer, the operating characteristics of the hammer remain generally constant and the only variable in prior art hammers is to provide a choke member in the air by-pass tube to establish the necessary volume of by-pass air to mix with the air discharged from the piston chamber to bail the hole.
According to the present invention there is provided a rock drill hammer operated by a pressurized fluid for providing hammer blows to a drill bit, the hammer having a cylindrical hammer body defining an internal chamber with a movable piston mounted in the chamber for axial reciprocal movement between an upper position adjacent the upper end of the chamber and a lower position, a drill bit axially extending into the chamber from the lower end and providing a surface for receiving the blows of the piston on its downward movement. An upper member defines the upper end of the chamber and a lower member defines the lower wall of the chamber, and a spacer means is removably attached within the chamber adjacent at least one of the members to fill a pre-determined portion of the chamber to alter the air consumption of the hammer at any given pressure.
It can be seen, therefore, that the present invention provides a fluid or air-operated hammer of the above sb/J~
1~7886~
type having interchangeable spacer members to, upon replacement r change the volume of the piston chamber of the hammer to enable the hammer to, upon such modification, utilize different volumes of air at a single pressure (i.e. depending upon the volume necessary sb/~ - 2a -.
7~61 to bail the hole). As the components of the hammer that determine the air flow amount is the volume of the piston chamber with the piston residing therein, spacers of various volumes placed in the chamber thereby alter the available chamber volume so that all the air delivered can be efficiently utilized to power the hammer prior to being discharged to bail the hole.
Description of the Drawings .
Figure 1 is a cross-sectional elevational view of a rock drill hammer with a reciprocating piston and having a spacer of one dimension according to the present invention;
Figure 2 is an enlarged sectional view of a portion of the hammer of Figure 1 and showing a spacer of a larger configuration to alter the hammer characteristics in accordance with the present invention;
Figure 3 is an exploded isometric view of the top member and spacer member of Figures 1 and 2; and Figure 4 is a view similar to Figure 2 of an alternative embodiment of the invention.
Description of the Preferred Embodiment -Referring to Figure 1, a fluid-operated rock drill hammer 10 is shown in position for drilling as resting on the bottom 12 of a borehole 11. The hammer 10 comprises a cylinder 13 with a drill chuck 14 supported at the lower end.
The drill chuck 14 receives a drill bit 15 retained in the chuck 14 by retaining ring 16 and axially projecting into the cylinder 13. The cylinder 13 is closed at its top end by a top sub 35 threadedly connected thereto which in turn is threaded to the drill string (not shown) for delivery of compressed air to the hammer.
A feed tube 17 is mounted coaxially in the cylinder 13 and extends from the upper end of the cylinder 13 toward the chuck 14 terminating just above the drill bit 15. At the upper end, the feed tube extends through an upper member 30 defining the top of the chamber to be in fluid flow communication with the ports of a check valve 32 housed in the top sub 35. The upper member 30 is retained in position by an upper annular guide member 34 and an annular washer 36 so that tightening the top sub 15 into the chamber 13 '7~61 completes the assembly.
The opposite end of the feed tube 17 is restricted or blocked by a choke 18 that blocks the fluid flow through the feed tube 17 providing higher presser in that portior, of the tube above the choke 18. A single set of pressurizing apertures 19 is provided in the wall of the feed tube 17.
The apertures 19 include four individual apertures spaced circumferentially around the tube 17 at a single axial position upstream of the plug 18. Exhaust ports 27 are provided in the tube below the choke 18.
An annular piston 22 is slidably mounted in the cylinder 13 to axially reciprocate within the chamber defined by the retaining ring 16 forming the lower wall member of the chamber and the upper member 36 defining the upper wall member. The piston 22 includes a channel 21 extending around the internal piston wall for fluid flow communication through longitudinal passageway 25 in the piston to the lower surface 20 of the piston 22. A second diametric channel 23 extends around the internal piston wall below the previous groove and is connected through longitudinal passageway 26 to the end face surface 24 at the upper end of piston 22. Thus, it is to be understood that through these various ports and passages pressurized air is delivered either to the upper surface of the piston 22 causing it to deliver a downward hammer-like blow to the bit 15, or to the lower surface 20 elevating the piston 22 to its upper position in preparation for the downward blow.
In accordance with the present inven~ion, the volume of the chamber defined between the upper member 30 and the retaining ring 16 is selectively modified by attach-ing to the upper member 30 a disc-like spacer 38. Thus, referring to Figures 1-3 (particularly Figure 3), it is seen that the upper member 30 defines an axially downwardly extending annular neck portion 31 surrounding the feed tube 17. The spacer 38 defines a concentric cGuntersunk opening for mating with the neck portion 31 with the upper annular surface 39 abutting the lower surface of the top member 30 and a lower surface 40 defining the top boundary of the piston chamber. The facing axially extending surfacas of the neck portion 31 of the spacer defines an annular groove 42 in axial alignment with openings 44 extending through the spacer member 38. A pair of removable mounting pins 48 are inserted in the openings 44 to seat within the groove 42 for retaining the spacer 38 on the member 30. The mounting pins 48 are held in position by the internal wall of the chamber during operation of the hammer.
Reference is now made particularly to Figure 2 which is an enlarged view of the upper portion of the hammer 10 showing the spacer 38 having greater axial dimension than the spacer member of Figure 1 so as to extend further into the chamber to displace air volume and thereby alter the air consumption characteristics of the hammer in accordance with a predetermined optimum air consumption.
Referring now to Figure 4, an alternative embodi-ment of the invention is shown. As therein seen, the spacer member 38a is a cylinder having an axially extending wall adjacent the inner wall of the chamber and thereby defining a reduced diameter upper portion of the chamber (as opposed to a reduced axial dimension to the upper chamber as in the previous Figures). To accommodate this configuration, it is noted that the piston 22 has a reduced diameter upper portion 22a that fi~s within the reduced diameter of the spacer 38a so that the piston is not restricted from its full axial reciprocal movement.
As before, the spacer 38a is removably retained in position by a shoulder 5a on the outer wall of the spacer engaging a mating annular shoulder within the chamber. Thus tightening the sub 15 against the washer 36 plaaes a retain-ing force on the spacer 38a during operation of the hammer, but permitting easy field replacement of a spacer of a lesser wall thickness to increase the chamber volume.
It should al~o be noted that this second configura-tion is easily adapted to attachment to the retaining ring16 at the lower end of the chamber (with the lower end of the piston requiring a reduced diameter portion similar to the upper portion herein above described) to similarly effectively change the volume of the chamber of the hammer , ...
:~17~86~
as desired in the field, with either one or both upper and lower spacers being used as desired.
Thus, it is seen that to change the hammer 10 .rom one set of operating characteristics utilizing a certain volume of air at a given pressure to utilizing a different volume of air at the same pressure, the top sub 15 is threadedly removed from the top of the cylinder 13 exposing the top guide 34 and the top member 3 a to be readily removed.
By removing the top member 30, the appropriate size spacer 38 can be inserted to alter the chamber volume in a manner that permits, for the most part, all the compressed air to be passed through the chamber prior to being exhausted through the bit for bailing the hole, thereby utilizing more of the compressed air for drilling the hole making the total operation more efficient.
Claims (4)
1. A rock drill hammer operated by a pressurized fluid for providing hammer blows to a drill bit, comprising:
a cylindrical hammer body defining an internal chamber;
a movable piston mounted in said chamber for axial reciprocal movement between an upper position adjacent the upper end of the chamber and a lower position;
a drill bit axially extending into said chamber from said lower end and providing a surface for receiving the blows of the piston on its downward movement;
an upper member defining the upper end of the chamber and a lower member defining the lower wall of said chamber; and spacer means removably attached within said chamber adjacent at least one of said members to fill a predetermined portion of the chamber to alter the air consumption of the hammer at any given pressure.
a cylindrical hammer body defining an internal chamber;
a movable piston mounted in said chamber for axial reciprocal movement between an upper position adjacent the upper end of the chamber and a lower position;
a drill bit axially extending into said chamber from said lower end and providing a surface for receiving the blows of the piston on its downward movement;
an upper member defining the upper end of the chamber and a lower member defining the lower wall of said chamber; and spacer means removably attached within said chamber adjacent at least one of said members to fill a predetermined portion of the chamber to alter the air consumption of the hammer at any given pressure.
2. Structure according to claim 1 wherein said spacer member is removably attached to said upper member.
3. Structure according to claim 2 wherein said member comprises a disc-like member generally coextensive with the diameter of said chamber and having a predetermined axial dimension to effectively change the axial dimension of said chamber.
4. Structure according to claim 2 wherein said spacer member comprises a cylindrical member having an outer diameter generally equal to the diameter of said chamber and a predetermined inner diameter to effectively change the radial dimension of said chamber.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US22730381A | 1981-01-22 | 1981-01-22 | |
| US227,303 | 1981-01-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1178861A true CA1178861A (en) | 1984-12-04 |
Family
ID=22852578
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000394041A Expired CA1178861A (en) | 1981-01-22 | 1982-01-13 | Drill hammer with variable air consumption |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU542647B2 (en) |
| CA (1) | CA1178861A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7617889B2 (en) | 2005-11-03 | 2009-11-17 | Rockmore International, Inc. | Backhead and drill assembly with backhead |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7794407B2 (en) | 2006-10-23 | 2010-09-14 | Bard Access Systems, Inc. | Method of locating the tip of a central venous catheter |
| WO2011097312A1 (en) | 2010-02-02 | 2011-08-11 | C.R. Bard, Inc. | Apparatus and method for catheter navigation and tip location |
-
1982
- 1982-01-05 AU AU79184/82A patent/AU542647B2/en not_active Withdrawn - After Issue
- 1982-01-13 CA CA000394041A patent/CA1178861A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7617889B2 (en) | 2005-11-03 | 2009-11-17 | Rockmore International, Inc. | Backhead and drill assembly with backhead |
| US8006784B2 (en) | 2005-11-03 | 2011-08-30 | Rockmore International, Inc. | Backhead and drill assembly with backhead |
Also Published As
| Publication number | Publication date |
|---|---|
| AU7918482A (en) | 1982-07-29 |
| AU542647B2 (en) | 1985-02-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |